Art of cracking hydrocarbon oils



Aug. 12, 1930. E. c. HERTHEL ART OF CRACKING HYDROCARBON OILS Filed March 30. 1928 INVENTOR fafa/7e #eff/76! www@ h v ATTORNEY ltitl Patented Aug. 12, 1930 UNITED STATES PATENT OFFiC EUGENE C. HERTHEL, F CHICAGO, ILLINOIS, ASSIGNOR Y'1.0 'SIN CLAIR REINING COM- PANY, 0F NEW YORK, N. Y., A CORPORATION 0F MAINE lA RT 0F CRACKING HYDROCARBON OILS Application filed March 30, 1928.

Petroleum oils as they come from the ground, probably without exception, contain sulphur. The amount of sulphur and the form in which the sulphur is present varies I In this aspect the sulphur is objectionable because it impairs the quality of the product. Frequently the sulphur is objectionable in another aspect, namely as a cause'of corrosion.

Cracking operations as commonly carried out usually involve the maintenance of high temperatures and high pressures, and in this latter aspect the presence of sulphur in stocks subjected to cracking operations consequently involves special ditlicult-ies because high temperatures tend to accelerate corrosion and high pressures increase the element of danger resulting from corrosion.

This invention relates to improvements in the cracking of heav sulphur-containing hydroca-rbon oils, suc asA gas oil, crude oil, topped crude oil, fuel oil, by distillation under superatmospheric pressure to roduce lighter hydrocarbon oils, slh as gaso `ne.

According to this invention, a desulphurizing agent is supplied to the cracking operation dispersed in raw oil supplied to the cracking operation in a manner such that circulation of the desulphurizing agent through zones in which the oil is externally heated is avoided and such that a contact between the oil and the desulphurizing agent particularly effective to combat corrosion is effected. Incarrying out the invention, oil vapors are taken 0E from a vaporizing zone under superatmospheric pressure and subjected to a reiuxing operation in which constituents of the vapors heavier than suitable as components of the desired product are condensed, reiiux condensate Afrom this reiuxing operation is circulated4 through a heating zone in which it is heated to a crack- Serial No. 265,862.

ing temperature to the vaporizing zone without permitting circulation of unvaporized oil from the vaporizing zone through the heatlng zone, raw oil is supplied to the vaporizing zone and the desulphurizing agent is also supplied to the vaporizing zone dispersed in this raw oil, and unvaporized oil including any unconsumed desulphurizing agent and any heavy products of the desulphurization is discharged from the vaporizing zone. Raw oil including the dispersed desulphurizing agent is with advantage passed in indirect heat exchanging relation wit-h the vapors in the reiiuxing operation before introduction into the vaporizing zone.`

Thus, all constituents of the raw oil supplied to the vaporizing zone circulated through the heating zone must first be vaporized in the vaporizlng zone and condensed in the reuxing operation, and any unconsumed desulphurizing agent and any heavy products ofthe desulphurization remain in the Vaporizing zone to be discharged therefrom with the unvaporized oil without being circulated through the heating zone. At the same time, all of the raw oil so supplied to the vaporizing zone is brought into intimate contact with the desulphurizing agent at elevated temperature. Corrosion diiculties seem to be more severe on surfaces in contact with oil vapors than on surfaces in contact with liquid oil, at the same temperature. j This invention however insures intimate contact between the desulphurizing agent and vaporized constituents as well as unvaporized constituents of the raw oil so supplied to the o eration. The maximum eifect of the desulp urizing agent may be secured by maintaining a substantial body of oil in the vaporizing zone. By passf ing the raw oil containing the dispersed desulphurizing agent in indirect heat exchanging relationwith the vapors inthe reiluxing operation, the oil is preheated and thus maintained in contact with the desulphurizing agent at elevated temperature for a prolonged period and for a period preceding introduction into the vaporizing zone. These several factors cooperate to make the desulphurizing agent more effective. By avoiding circulation of the desulphurizing agent or heavy 100 alkali. The invention is particularly adapted to utilize finely divided 'solid desulphurizing agents supplied in suspension in raw'oil."

The invention is also adapted to utilize liquid-or semi-liquid desulphurizing agents supplied in emulsion in raw oil. The invention is articularly adapted to utilize lime as the esulphurizing agent and lime is a particularly advantageous desulphurizing agent to 'use in.carrying out this invention.

This' invention thus provides an advantageous method of combatting corrosion in the cracking of sulphur-containing hydrocarbon oils by distillation under superatmospheric pressure and is also effective in reducing thev sulphur content of the oil products of such operations.

The invention will be urther described in connection with the accompanying drawingsv which illustrate, diagrammatically and conventionally, in elevationand partly in section and with parts broken away, one form of apparatus adaptedfor carrying out the process of the invention. It will be understood that the following more detailed description of the invention in connection with this particular form of apparatus is intended. to exemplify the invention and that the invention can be carried out in other and dif ferent forms of apparatus.

The pressure still illustrated comprises a vaporizing drum 1 and a battery of heating tubes 2 arranged in the heating iiue'of a heating furnace 3. A reflux tower 4 is ar ranged above the vaporizing drum 1. Va-

pors escape from the vaporizing drum 1 to the lower end of the reflux tower 4 through vapor line 5 and vapors remaining uncondens'ed escape from the upper end of the reflux tower 4 through vapor line 6 to a condenser 7. Condenser 7 is arranged to discharge into receiver 8 from which the dis-l tillate product of the operation is discharged through connection 9 and uncondensed vapors and gases through connection 10. Pressure in the-system may be maintained and regulated by means of valve 11 in the vapor line 6 between the reflux tower 4 and the condenser 7 or by means of suitable valves arranged beyond the condenser or receiver. Reflux condensate from the lower end of the reflux tower 4 is discharged through connection 12 to the pump 13 which then forces this oil mixture through connection 14 upwardly through the heating tubes 2 through connection 16 to the vaporizing drum 1. The oil is heated to a cracking temperature in the heating tubes 2. Tar line 17 is provided for discharging unvaporized oil from the vaporizing drum during operation. Connection 18 is provided for initially charging the still and for pumping out the still at the end of a run. Connection 19 is provided for supplying cooling oil to the bearings of the pump 13. Connection 20 with closure valve 21 is provided for use in bringing the still into operation. Connection 22, for direct introduction 4of a reiiuxing medium, and cooling coil 23 are provided for effecting or controlling the reluxing operation in tower 4. Raw oil is supplied through connection 24, either around the vapor tubes 25 in the reflux tower 4 or through connection 26, through connection 27 to the vaporizing drum 1.

The particular type of pump illustrated, designated 13, is described in more detail in an application of Thomas d C. Tiii't filed June 7, 1927, Serial No. 197,209. The particular type of closure valve illustrated, designated 21, is described in more detail in my application filed January 12, 1923, Seriall To bring the still system illustrated to operating conditions of temperature and pressure, with the valve 21 open the still is charged with enough oil to lill the drum 1 say half full, pump 13 is started to maintain circulation of the oil charge from the drum 1 through the heating tubes 2 back to the drum 1, lires are started in the heating furnace 3, drips are taken off, valve 11 is then closed until the desired operating pressure is reached, valve 21 is then closed very gradually and valve 11 is radually opened and regulated to maintain t e desired operating pressure, and the supplypf raw oil and discharge of unvaporized oil is begun. For the production of gasoline from gas oil, for example, pressures in the neighborhood of 90-125 pounds per square inch may be eniployed, or higher pressures up to say 300 pounds per square inch or more may be employed. In general, higher pressures are employed with lighter charging stocks or to produce lighter distillate products. f In any particular case the temperature will be determined by the pressure used.

The initial charge of oil may consist of the same stock to be vsupplied during operation or, particularly if the stock to e supplied during operation contains a large amount of objectionable sulphur, the initial charge may consist of some other stock containing a relatively small amount of objectionable sulphur or, if the stock to be supplied during operation is a crude or topped crude or fuel oil or contains a large amount of tarry or pitchy constituents, the initial charge may consist of a clean gas oil stock.

In carrying out the present invention in the apparatus illustrated, after the still system has been brought to operating conditions of temperature and pressure, the introduction of raw oil, the sulphur-containing stock, into the vaporizing drum 1 through connections 24 and 27 together With a desulphurizing agent dispersed therein is begun. The raw oil so supplied to the vaporizing drum 1 may'contain in suspension, for example, from 1/4 to 4 pounds of `hydrated lime per barrel (42 gallons). This raw oil containing the dispersed desulphurizing agent may be supplied to the vaporizing drum 1 after passing around the vapor tubes in the reflux tower 4 or may be supplied to the vaporizing drum 1 through connection 264 or may be supplied partly in each way. For example, therefluxing operation carried out in tower 4 may be controlled, in whole or in part, by regulated by-passing of such raw oil through connection 26, the rest passing around the vapor tubes in the reflux tower 4. ln the vaporizing drum 1 the constituents of the raw oil to be passed through the heating tubes 2 are vaporized and escape to the reflux tower 4 through vapor line 5; in the reliux tower 4 these vaporized constituents are condensed and supplied as condensate to the heating tubes 2 through connection 12.A Any unconsumed desulphurizing agent and heavy products of the desulphurization together with any unvaporized heavy constituents of the raw oil remain as a residue in the vaporizing drum. For example, a gas oil raw stock may be completely vaporized upon introduction into the vaporizing drum 1 or a crude or topped crude stock or fuel oil stock may be vaporized only in part leaving heavy constituents or tarry or pitchy constituents in the residue. The residue collecting in the vaporizing drum 1 also includes heavy constituents discharged from the heating .tubes 2. This residue is not permitted to circulate through the heatmg tubes 2, but is discharged through tar line 17.I The reflux condensate collecting in the lower end of tower 4 includes heavy constituents condensed fromthe cracked vapors of the oil discharged into the vaporizing drum 1 from the heating tubes 2 as Well as vaporized then condensed constituents of raw oil introduced into the vaporizing .drum 1 through connection 27. rEhe refluxmg operation carried out in tower 4 is regulated to condense all constituents of the vapors passing therethrough heavier than suitable as components of the desired distillate product suitable to be supplied to the heating tubes 2 to be heated to a cracking temperature therein. For the production of gasoline, for

example, the refluxing operation may be regulated so that the temperature of the vapors medium through connection 22 or by the regulated circulation of a cooling medium, water or cool oil for example, through cooling coil 23. A part of the distillate product may be -reintroduced through connection 22 or a clean gas oil stock may be introduced through this connection,'for example, as a refluxing medlum. Raw oil circulated through the reux tower 4 around the vapor tubes 25 is thereby preheated and raw oil containing the dispersed desulphurizing agent may thus with advantage be heated to an elevatedtemperature While in contact with the desulphurizing agent before introduction into the vaporizing drum 1 and before any possibility of escape by vaporization of any of the raw oil constituents.

The apparatus illustrated, including the vaporlznig drum 1, the reflux tower 4 and connections 5, 12, 14, 16, 20 and 27, are with advantage lagged or thermally insulated.

rlhe character of the desulphurizing agent used permitting, the residue including any unconsumed desulphurizing agent and any heavy products of the desulphurization dis,- charged from the vaporizing zone may be subjected to treatment for recovery of the desulphurizing agent. Where cupriferous desulphurizing agents are used, for example, the residue discharged from the vaporizing zone, either before or after distillation therefrom of lighter oil constituents, may be cooled and the cooled residue permitted to settle or subjected to a filtering operation for the separation of the metallic values and this separated material roasted or otherwise treated to render it again active to be reused in the process. ln general, where lime is used for example, any unconsumed desulphurizing agent and any heavy products of the desulphurization may be separated from the discharged residue by settling or filtration after cooling.

1 claim:

1. In cracking sulphur-containing hydro carbon oils by distillation under superatmospheric pressure, the improvement which comprises taking 0H oil vapors from a Vaporizing "zone under superatmospheric pressure and subjecting such oil yvapors to a reiuxing operation to condense those constituents of the vapors heavier than suitable as components of the desired distillate product, circulating reflux condensate from the said reduxing operation through a heating zone to the said vaporizing zone without permitting cir- *ing operation through culation of unvaporized oil from the said va-` to, whereby circulation through the said heating zone of the desulphurizing agent and heavy products of the desulphurization is avoided, and discharging unvaporized oil including any unconsumed desulphurizing agent and such heavy products of the desulphurizaton from the said vaporizing zone.

2. In cracking sulphur-containing hydrocarbon oils by distillation under superatmosplieric pressure. the improvement Which comprises taking oit oil vapors from a VaporizingV zone under superatinospheric pressure and subjecting such oil vapors to a refluxing operation to condense those constituents of the vapors heavier than suitable as components of the desired distillate product, circulating reflux condensate from the said refluxa heating zone to the said vaporizing zone Without permitting circulation of unvaporized oil from the said vaporizing zone through the said heating zone and heating the oil to a cracking teinperature in the said heating zone, passing raw oil in indirect heat exchangingrelation With the vapors in the said refluxing operation thereby preheating the raw oil and supplying such preheated raw oil to the said vaporizing zone, whereby all constituents of such raw oil circulated through the said heating zone must first be vaporized in the said vaporizing zone and condensed in the said reiuxing operation, supplying a desulphurizing agent to the said vaporizing zone dispersed in such raw oil passed in heat exchaning relation with the vapors in the said reiiuXing operation and then supplied to the said vaporizing zone, whereby the raw .oil containing the dispersed desulphuriz'ing agent is preheated before introduction intov the vaporizing zone and whereby circulation through the said `heating zone of the desulphurizing agent and heavy products of .the desulphurization is avoided, and discharging unvaporized voil including any unconsumed desulphurizing agent and such heavy products of the desulphurization from the said vaporizing zone. .s

3. 1n cracking sulphur-containing hydrocarbon oils by distillation under superat- Inospheric pressure, the improvement which comprises taking oit oil vapors from a vaporizing zone under superatmospheric pressure and subjecting such oil vapors to a. reluXing operation to condense those constituents of the vapors heavier than suitable as components of the desired distillate product, circulating reiiuX condensate from the said reiuXing operation through a heating zone to the said vaporizing zone without permitting circulation of unvaporized oil from the said vaporizing zone through the said heating zone and heating the oil to a cracking temperature in the said heating zone, supplying raw oil to the said vaporizing zone and supplying lime to the vaporizing zone in suspension in such raw oil supplied thereto, and discharging unvaporized oil including suspended lime and lime-containing reaction products from the said vaporizing zone, whereby circulation through the said heating zone 0f oil including suspended lime or lime-containing reaction products is avoided.

4. In cracking sulphur-containing hydrocarbon oils by distillation under superatmospheric pressure, the improvement which coinprises taking ofi oil vapors from a Vaporizing zone under superatmospheric pressure and subjecting such oil vapors to a refluxing operation to condense those constituents of the vapors heavier than suitable as components of the desired distillate product, circulating reiiux condensate from the said reiuxing operation through a heating zone to the said vaporizing zone Without permitting circulation of unvaporized oil from the said vaporizing zone through the said heating zone and heating the oil to a cracking temperature in the said heating zone, passing raw oil in indirect heat exchanging relation with the vapors in the said reliuxing operation and supplying such preheated raw oil to the said vaporizing Zone, supplying lime to the said vaporizing zone in suspension in such raw oil passed in heat exchanging relation with the vapors in the said reiiuxing operation and then supplied to the said vaporizing zone.l and discharging unvaporized oil including suspended lime and lime-containing reaction products from the said vaporizing Zone,

Vwhereby circulation through the said heating zone of oil including suspended lime or limecontaining reaction products is avoided.

In testimony whereof, I have subscribed my name.

EUGENE C. HERTHEL.

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